1. Field of Invention
The invention relates to an ink pellet formed of hot melt ink in the solid state and used for an ink jet recording apparatus.
2. Description of Related Art
In an ink jet recording apparatus utilizing hot melt ink, the ink is heated and melted in an ink melting section provided with a heater. An ink droplet is then ejected from a nozzle onto, for example, a sheet of paper while main-scanning a recording head having a large number of nozzles, to thereby print characters or diagrams onto the sheet of paper.
Since the hot melt ink becomes solid at room temperature, it is normally processed into an ink pellet of a predetermined shape for storage. The hot melt ink is supplied to the ink melting section in the pellet form when the ink supply section becomes empty. If an operator directly touches the ink pellet at this time, stains or grease on the operator's hands are adhered to the ink pellet and deteriorate the quality of the hot melt ink.
As shown in FIG. 17, a conventional structure disclosed in U.S. Pat. No. 4,823,146 includes an ink holder 81 formed in the shape of a cup. The ink pellet 83 is formed so as to correspond to the internal shape of the ink holder 81 and the ink pellet 83 is stored in the ink holder 81. When ink runs out, the ink holder 81 is arranged such that an open end of the ink holder 81 is in contact with a supplying opening 82 of an ink melting section. The back side of the ink holder 81 is pressed by hand to be collapsed and deformed, with the result that the ink pellet 83 is supplied to the supplying opening 82 without being directly touched by the hands of the operator.
However, in the above-mentioned conventional structure in which a single ink pellet 83 is accommodated in the ink holder 81, only one ink pellet 83 is removed by the one operation of arranging the ink holder 81 above the supplying opening 82 and pressing to collapse and deform the ink holder 81. Therefore, in the case where the ink pellet 83 includes only a small amount of hot melt ink, the amount of ink supplied to the ink melting section by the one operation is small so that the ink frequently runs out. If the supply amount of ink is increased a predetermined amount in order to reduce the frequency of the ink empty condition, the operator must supply a greater number of the ink pellet 83 which increases the work load of the operator.
On the other hand, if the ink pellet 83 is formed to include a larger supply of hot melt ink so as to reduce the frequency of the above-mentioned ink empty condition and the work load of the operator, the supply amount is liable to be excessive in relation to an amount of ink normally consumed in use of a typical ink jet recording apparatus. Accordingly, the hot melt ink is heated for a long time in the ink melting section reducing the quality of the ink.
As shown in FIG. 18, U.S. Pat. No. 4,636,803 discloses a structure in which a plurality of ink pellets 71, each formed of a small amount of hot melt ink, are stored in a tubular housing 75. When an ink melting section 72 runs out of ink, the ink pellet 71 is moved to a discharge opening 75A by the rotation of a driving shaft 73 by a motor 74 to move the ink pellet 71 from the discharge opening 75A into the ink melting section 72. With this structure, storage and supply of the ink pellet 71 is provided without the need for operator intervention, thereby not increasing the burden to an operator when the number of ink pellets to be supplied is increased.
However, with the above-mentioned structure, the entire bottom surface of the ink pellet 71 contacts with an inner wall surface of the housing 75 so that, when the ink pellet 71 is moved, the friction force is large. The friction force increases in proportion to the stored number of ink pellets 71. Therefore, to smoothly move the ink pellet 71 requires that the ink supplying apparatus be provided with a mechanism such as a driving shaft 73 capable of providing a sufficiently large driving force in relation to the large friction force. This causes the ink supplying apparatus to be large and complex.
To solve the above-mentioned problem that hot melt ink is heated for a long time in the ink melting section, another structure as described below has been proposed. With this structure, an ink jet recording apparatus is provided with an ink supplying apparatus in which an ink pellet formed of a small amount of hot melt ink is stored in an accommodating channel section of an ink supplying system relative to an ink melting section. The ink pellet is then discharged from the accommodating channel section to the ink melting section upon the ink empty condition.
Accordingly, the storage and supply of the ink pellet can be performed without the intervention of the operator so that the burden to an operator is not increased even if the number of the ink pellets to be supplied is increased. However, when the ink pellet is fed along the accommodating channel section, if the width of the accommodating channel section and the size of the ink pellet do not correspond, the ink pellet may rotate as it is fed along the accommodating channel section changing its orientation. If this happens, the ink pellet may clog the accommodating channel section and be stuck therein. If the ink pellet is stuck, the operator has to unclog the accommodating channel section and free the ink pellet. This requires operator intervention where the aim of the ink supplying apparatus discussed above was to supply the ink pellet without the intervention of the operator.